Reduced calorie fats which are made from triglycerides containing medium and long chain fatty acids have been disclosed for use as a replacement for conventional triglyceride fats in food products. See, for example, Seiden; U.S. Pat. No. 5,288,512; Issued Feb. 22, 1994 which discloses reduced fat compositions comprising at least about 15% by weight triglycerides selected from the group MML, MLM, LLM and LML triglycerides and mixtures thereof; wherein M=fatty acids selected from the group consisting of C.sub.6 to C.sub.10 saturated fatty acids, and mixtures thereof, and L=fatty acids selected from the group consisting of C.sub.17 to C.sub.26 saturated fatty acids, and mixtures thereof, and wherein the fat has the following fatty acid composition by weight percent:
(a) from about 15% to about 70% C.sub.6 to C.sub.10 saturated fatty acids; PA1 (b) from about 10% to about 70% C.sub.17 to C.sub.26 saturated fatty acids; PA1 (c) not more than about 10% fatty acids selected from the group consisting of C.sub.12:0 and C.sub.14:0, and mixtures thereof, PA1 (d) not more than about 20% fatty acids selected from the group consisting of C.sub.18:1, C.sub.18:2, C.sub.18:3 and mixtures thereof, and PA1 (e) not more than 4% C.sub.18:2 fatty acids. PA1 (a) from about 15% to about 70% C.sub.6 to C.sub.10 saturated fatty acids; PA1 (b) from about 10% to about 70% C.sub.17 to C.sub.26 saturated fatty acids; PA1 (c) not more than about 10% fatty acids selected from the group consisting of C.sub.12:0 and C.sub.14:0, and mixtures thereof, PA1 (d) not more than about 20% fatty acids selected from the group consisting of C.sub.18:1, C.sub.18:2, C.sub.18:3 and mixtures thereof, and PA1 (e) not more than 4% C.sub.18:2 fatty acids.
Seiden taught that the reduced calorie fats disclosed therein could be prepared by a wide variety of techniques such as by random rearrangement of long chain triglycerides and medium chain triglycerides, esterification of glycerol with a blend of the corresponding fatty acids, transesterification of a blend of medium and long chain fatty acid methyl esters with glycerol and transesterification of long chain fatty acid glycerol esters with medium chain triglycerides. Processes for preparing reduced calorie fats such as those disclosed in Seiden et al are also described, for example, in U.S. Pat. No. 5,142,071 to Kluesener et ai; Issued Aug. 25, 1992 and U.S. Pat. No. 5, 142,072 to Stipp et al; issued Aug. 25, 1992.
Unfortunately, reduced calorie fats prepared according to these prior processes are slower to crystallize to the thermodynamically stable beta structure than conventional triglycerides. It has now been found that the rate of crystallization of reduced calorie fats containing reduced calorie triglycerides is dependent on the distribution of MML and MLM triglycerides present in the reduced calorie fat. Reduced calorie fats prepared according to prior processes typically contain less than about 40% of the MLM long chain fatty acid 2-position isomers. It has now been found that, surprisingly, reduced calorie fats comprising mixtures of reduced calorie triglycerides which are enriched in MLM long chain fatty acid 2-position isomers (e.g., which contain at least about 40% of the long chain fatty acid 2-position isomers) exhibit rapid crystallization into the stable beta phase (as measured by x-ray diffraction analysis and by differential scanning calorimetry) compared to reduced calorie fats comprising mixtures of reduced calorie triglycerides which contain less than about 40% of the long chain fatty acid 2-position isomer. In particular the amount of time required for the reduced fat to crystallize into the stable beta phase can be reduced from about 24 hours for a reduced calorie fat having a random distribution of MLM and MML triglyceride to almost instantaneous for reduced calorie fats comprising 100% MLM triglycerides.
It has also now been found that reduced calorie which are enriched in the MLM long chain fatty acid 2-position isomer are more resistant to thermal stress, more bloom stable, exhibit greater compatibility with other fats and fat isomers and have more desirable melting points than reduced calorie fats comprising mixtures of reduced calorie triglycerides which contain less than about 40% of the long chain fatty acid 2-position isomer.